Perovskite Solar Cells Using Carbon Nanotubes Both as Cathode and as Anode

Organic–inorganic halide perovskite solar cells have received much attention because they achieve high power conversion efficiencies while providing the advantages of thin-film solar cells, namely, solution processability and potentially low fabrication costs. However, at the current level of halide perovskite solar cell technology, these advantages cannot be maximized because of structural and material limitations. Here, we provide a solution to these problems by replacing conventional metal and metal oxide electrodes with carbon nanotube electrodes. We also simplified the structure to achieve entirely solution-processable perovskite solar cells. Through this study, we demonstrate the function of carbon nanotubes as both the anode and the cathode in perovskite solar cells. Economic modeling suggests that this novel architecture reduces costs dramatically. This work realizes innovations in the materials, costs, and processing of inverted-type perovskite solar cells

Carbon Nanotubes versus Graphene as Flexible Transparent Electrodes in Inverted Perovskite Solar Cells

Transparent carbon electrodes, carbon nanotubes, and graphene were used as the bottom electrode in flexible inverted perovskite solar cells. Their photovoltaic performance and mechanical resilience were compared and analyzed using various techniques. Whereas a conventional inverted perovskite solar cells using indium tin oxide showed a power conversion efficiency of 17.8%, the carbon nanotube- and graphene-based cells showed efficiencies of 12.8% and 14.2%, respectively. An established MoO₃ doping was used for  carbon electrode-based devices. The difference in the photovoltaic performance between the carbon nanotube- and graphene-based cells was due to the difference in morphology and transmittance. Raman spectroscopy, and cyclic flexural testing revealed that the graphene-based cells were more susceptible to strain than the carbon nanotube-based cells, though the difference was marginal. Overall, despite higher performance, the transfer step for graphene has lower reproducibility. Thus, the development of better graphene transfer methods would help maximize the current capacity of graphene-based cells